This mentored career development award seeks to combine a program of focused research, mentorship, and didactics to provide advanced training which will facilitate my transition into an independent patient-oriented research career focusing on developing, delivering, and evaluating technology-enhanced interventions targeting substance use (including illicit drugs and non-medical use of prescription drugs) and HIV risk reduction (HIV-related sexual risk behaviors [HIV SRBs]; e.g., inconsistent condom use, multiple partners, sex while intoxicated; and prevention of injection drug use) among at-risk emerging adults (EAs). Research regarding substance use and HIV SRBs among EAs has generally focused on alcohol use among college students from campus settings; however, substance use and HIV (and other associated Sexually Transmitted Infections) disproportionately occur among young people living in urban, low-resource communities, particularly African Americans. At the daily and event-level, substance use and HIV SRBs may be influenced by social cognitive factors (e.g., motivations for substance use/HIV SRBs, self-efficacy to engage in safe sex/not use substances) in addition to the pharmacology of specific substances. However, daily process data focusing on social cognitive factors, substance use, and HIV SRBs among EAs, especially those from noncampus settings, is lacking, yet would be highly informative to the development of tailored substance use and HIV risk reduction brief interventions for EAs. The Emergency Department (ED) is a critical venue for accessing at-risk EAs engaging in substance use and HIV risk behaviors. Research shows high rates of substance use and HIV SRBs among EA patients in the ED, yet no intervention exists for EAs in this setting. The ED may be the only opportunity to intervene with these young people because EAs in urban, low-resource settings often lack a primary care provider during the transition from pediatric to adult medicine, may be un-insured or under-insured, and may not be involved in a traditional college campus setting. Further the use of technology (e.g., mobile phones) is relatively ubiquitous among this age group, and most prefer technology-based communication (e.g., text messaging), therefore interventions for EAs may be enhanced by this type of technology. My career goals are to develop expertise: 1) in the use of technology to assess daily relationships between social cognitive factors, substance use (i.e., illicit drugs, including injection, and non-medical use of prescription drugs), and HIV SRBs among EAs; and 2) in the development and evaluation of substance use and HIV SRB interventions, applicable in low-resource community and healthcare settings such as the urban ED, through the integration of novel technologybased communication. Aims of the proposed training plan are to: 1) Increase knowledge of the content areas of social cognitive factors, substance use, HIV SRBs, and related consequences (e.g., HIV/STI, injury) among EAs, 2) Learn techniques for using technology to assess and analyze daily-level data regarding social cognitive factors, substance use, and HIV SRBs among EAs, 3) Acquire skills to develop, implement, and evaluate a technology-augmented intervention for substance use and HIV SRBs among EAs in the ED, and 4) Further training in the responsible conduct of research with human subjects. These training aims are closely aligned with specific research aims: 1) Among EAs recruited from an ED setting, conduct prospective, longitudinal, daily data collection using mobile text message-based assessment for substance use (i.e., illicit drugs and prescription drugs used non-medically)and HIV risk behaviors (primarily SRBs, but also injection drug use) including measuring critical social cognitive factors that may underlie the relationships between substance use and HIV risk (e.g., motives for substance use/risky sex, self-efficacy related to condom use), and 2) Based on findings from the prospective study conducted in research Aim 1, develop and pilot test a tailored intervention (e.g., substances used, partner type, social cognitive factors, and gender) for EA patients in the ED focusing on reducing substance use and HIV SRBs, which will be enhanced through the use of mobile phone text messages targeting substance use and HIV SRBs. I will accomplish these research and training goals through close mentorship from a team with expertise in these content areas, didactic coursework, and directed readings.